rth: change the working directory on Windows
rth: change the working directory on Windows

The tests need to change the working directory when executing on Windows
as RPATH is not supported on the platform.  The current working
directory gets precedence over `PATH` for library lookup.  This allows
the last of the Evolution tests pass on Windows.

stephentyrone/swift,atrick/swift,JGiola/swift,JGiola/swift,xedin/swift,harlanhaskins/swift,glessard/swift,apple/swift,stephentyrone/swift,lorentey/swift,benlangmuir/swift,hooman/swift,CodaFi/swift,karwa/swift,atrick/swift,aschwaighofer/swift,lorentey/swift,hooman/swift,gregomni/swift,ahoppen/swift,benlangmuir/swift,aschwaighofer/swift,shahmishal/swift,stephentyrone/swift,rudkx/swift,gregomni/swift,lorentey/swift,allevato/swift,shahmishal/swift,jckarter/swift,airspeedswift/swift,gribozavr/swift,jckarter/swift,harlanhaskins/swift,jmgc/swift,harlanhaskins/swift,harlanhaskins/swift,gregomni/swift,xwu/swift,apple/swift,airspeedswift/swift,gribozavr/swift,parkera/swift,jmgc/swift,gribozavr/swift,xedin/swift,devincoughlin/swift,xwu/swift,aschwaighofer/swift,xedin/swift,jmgc/swift,karwa/swift,xedin/swift,gribozavr/swift,xwu/swift,CodaFi/swift,allevato/swift,hooman/swift,jmgc/swift,karwa/swift,shahmishal/swift,airspeedswift/swift,CodaFi/swift,JGiola/swift,harlanhaskins/swift,devincoughlin/swift,tkremenek/swift,devincoughlin/swift,nathawes/swift,allevato/swift,karwa/swift,tkremenek/swift,parkera/swift,jckarter/swift,tkremenek/swift,allevato/swift,apple/swift,CodaFi/swift,glessard/swift,CodaFi/swift,shahmishal/swift,karwa/swift,lorentey/swift,lorentey/swift,xedin/swift,shahmishal/swift,benlangmuir/swift,tkremenek/swift,roambotics/swift,nathawes/swift,stephentyrone/swift,parkera/swift,nathawes/swift,rudkx/swift,aschwaighofer/swift,glessard/swift,rudkx/swift,jckarter/swift,roambotics/swift,rudkx/swift,shahmishal/swift,allevato/swift,nathawes/swift,shahmishal/swift,sschiau/swift,glessard/swift,parkera/swift,roambotics/swift,sschiau/swift,lorentey/swift,JGiola/swift,atrick/swift,JGiola/swift,xwu/swift,xedin/swift,jmgc/swift,aschwaighofer/swift,hooman/swift,tkremenek/swift,benlangmuir/swift,parkera/swift,airspeedswift/swift,gribozavr/swift,xedin/swift,jckarter/swift,jmgc/swift,stephentyrone/swift,roambotics/swift,parkera/swift,tkremenek/swift,apple/swift,sschiau/swift,ahoppen/swift,sschiau/swift,ahoppen/swift,airspeedswift/swift,karwa/swift,sschiau/swift,stephentyrone/swift,roambotics/swift,allevato/swift,jmgc/swift,hooman/swift,JGiola/swift,karwa/swift,nathawes/swift,ahoppen/swift,devincoughlin/swift,karwa/swift,harlanhaskins/swift,gribozavr/swift,parkera/swift,gribozavr/swift,atrick/swift,devincoughlin/swift,gribozavr/swift,CodaFi/swift,apple/swift,ahoppen/swift,xwu/swift,glessard/swift,ahoppen/swift,rudkx/swift,xwu/swift,jckarter/swift,shahmishal/swift,sschiau/swift,atrick/swift,jckarter/swift,stephentyrone/swift,nathawes/swift,benlangmuir/swift,gregomni/swift,devincoughlin/swift,gregomni/swift,hooman/swift,sschiau/swift,gregomni/swift,hooman/swift,lorentey/swift,benlangmuir/swift,rudkx/swift,atrick/swift,airspeedswift/swift,aschwaighofer/swift,apple/swift,sschiau/swift,airspeedswift/swift,lorentey/swift,devincoughlin/swift,xwu/swift,roambotics/swift,devincoughlin/swift,glessard/swift,parkera/swift,nathawes/swift,harlanhaskins/swift,tkremenek/swift,xedin/swift,allevato/swift,aschwaighofer/swift,CodaFi/swift